Now that the concept of improvising session involving an instrument with an acoustic pedigree and another which comes from the world of electronics has become commonplace, the question becomes not how it’s done, but how well the parts fit. Very well indeed, would be the answer for these international duos, but this is so because each set handles the duet in a different manner.

Köln-based saxophonist Georg Wissel also works without electronics in setting with the likes of drummer Paul Lytton, but on Corpus Callosum he chooses to play prepared alto saxophones the better to connect with the custom-made electronic instruments of sound designer and fellow Köln resident Joker Nies, who has worked with other saxophonists like John Butcher. Although his saxophones and clarinets are not “prepared” on Uncertain Statistics, Lithuanian Liudas Mockūnas is an old-hand at electro-acoustic improvising, having worked with Dane Jakob Riis, who uses laptop and mixing board feedback in many contexts. Meanwhile British alto and baritone saxophonist Simon Rose, who also excels in solo playing, sticks very much to an acoustic foundation on Fauna. His partner here is Belfast-based Californian Paul Stapleton, who uses the Bonsai Sound Sculpture or BoSS, which he and Neil Fawcett invented in 2010. It combines a repurposed turntable, DIY electronics, amplified metallic percussion and strings.

The most traditionally satisfying of the discs here is Fauna where the usual strategy is for Rose to display different, usually extended, saxophone effects while Stapleton provides the backing as if he was a pianist or a bassist. Although episodes of staccato flanges, ring modulator-like thwacks and pulsating vibrations are heard throughout, the sound artist’s most common forefront properties are aviary like chirps, jittery buzzes and string resonation. Not only can the BoSS echo and complement Rose’s reed timbres, but there are suggestions that some saxophone parts as well as altissimo whistling result from Stapleton’s real-time processing.

Stimulating and outstanding is “Shift” which is built around the contrast between stentorian saxophone growls and delicate resonations from the BoSS. Here Stapleton’s interface is shaped into string-like strums and cascades as Rose exactingly constructs his tonal expansion from irregular pressures, vibrations and squeaks, culminating in a bubbling, circular-breathed exercise. Other pieces like “Felt” finds the BoSS’ premeditated shakes and vibrations causing Rose to turn to circular breathing and reed sucks, while “Zeiteinheit” concludes as a slow-moving exercise in basement tones as the saxophonist deepens his output from slurps and tongue-stops to shaking snorts in response to equally compelling aviary-like shrills from Stapleton.

At the other extreme on Corpus Callosum the preparations attached to Wissel’s woodwinds often make it difficult to distinguish his timbres from those of Nies’ electronics. Other times the profound contrast between acoustically sourced and mechanically created quivers is used to good effect, as the sound designer’s loops and whines and the reedist’s whistles and flutter tonguing create complementary sonic exultation. On “Accessorius” for instance Wissel’s throaty mumbles from deep within his horn’s body tube swiftly transform into staccato whistles to meet Nies’ grinding output that in pitch and reach suggest deconstructed cries from a mechanized rooster trapped in a wind tunnel. Similarly on “Callosum”, stretched and looped cries propelled by electronics so that they resemble rocket-launching detonations are matched by harsh yelps and stuttering vibrations from the reed man. However the major contrast, as expressed on tracks such as “Trochlearis”, is that the basic humanness of the saxophonist in the form of mouthpiece sucking and irregularly fluttered lines can always be discerned throughout the improvisations. Close approximations from motor-driven wiggles and looping signals may almost replicate Wissel’s output, but still lack the emotional tinge.

“Glossopharyngeus” and “Abducens”, the final and penultimate tracks show the two conspiring to blend individual output into a notable climax. Breaking away from reed sound replications after watery bluster from his machine has been subsumed by Wisssel’s swelling stentorian vibrations and agitated tongue slaps Nies downshifts to blurry and buzzing wave forms. By the finale, despite the equivalent harshness, reed slurps nestle comfortably within the backwash of processed oscillations.

Uncertain Statistics draws on both of the other duos’ strategies. But with fewer tracks, and a longer history together, Mockūnas and Riis have more space for sound elaboration plus have established separate identities for each improviser. Mockūnas’ extended tongue slaps, smears and key slaps establish an ersatz percussiveness that frequently underlines the pieces. Meanwhile Riis’ processing is more limpid and winnowing, specializing in calming burbles. Again though, at points, there is a suggestion that some of the audible reed-like tones may actually be live processing from the laptop.

Almost twice the length of any other track, “Method of Moments” works through individual expressions from both participants. With his woodwinds neither processed nor altered with preparations, Mockūnas uses standard extended techniques to make his point(s). Shrill whistles and metal scrapping, reed bites and tongue slaps are his common currency, as well as episodes of extended circular breathing plus sounding two saxophones at the same time. The first technique comes to the fore when he’s up against static flanges from Riis’ computer that move the partners’ output to blurry wave forms. Late, paced trills plus narrowed animalistic reed cries are used to cut through a nearly radioactive sounding cloud of blurred pulsations. When the processing retreats to the background, Mockūnas creates a beautifully modulated display of flutter tonguing. Riis’ sympathetic response with what could be the reverberations from rubbed Tibetan bowls, is serene enough to prove that intersection between textures can arise, no matter the speed or pitch.

While each creation here is a bit out-of-the-ordinary, the duos prove that with the right partners’ electro-acoustic interface can be a satisfyingly challenging as music produced by any other combination.